Leader of the House Andrew Lansley yesterday sought to pacify charities worried that the second part of the bill, which concerns third party spending in the run up to the election, would gag their right to campaign.

Lansley said third parties would only face spending caps if the aimed to "promote or procure the electoral success" of a political party.

In a statement, he said: "We have listened and acted, as I said we would do," before adding that he was confident upcoming amendments would ensure concerns raised "have now been met".

However, PR’s industry bodies scorned a lack of reference to the widely-criticised first part of the bill, which seeks to introduce a statutory register of lobbyists without including in-house PRs.

Phil Morgan, director of policy labelled the register proposals "a mess" and called for a new bill to be brought forward.

"These amendments show that the Government are prepared to listen to stakeholders and amend their position in an attempt to meet their concerns, but only on part two of the bill," Morgan said.

He added: "If the Government can make amendments to part two of the bill, they can make amendments to part one as well, but it may not be enough. The register proposals are so poor and are getting such little support that following the select committee Chairman’s advice and bringing forward a better Bill seems like common sense."

PRCA director general Francis Ingham added: "The Government continues to ignore the major problem with this much-criticised bill – the proposals for registering lobbyists. They have so far failed to listen to Graham Allen’s Select Committee, the lobbying industry, and everyone who is campaigning for wider transparency."